Auto Electronics

CMOS Image Sensors Gather Momentum for Safety

Safety is on the mind of every automaker. A number of vision-sensing technologies are being pursued to tackle this problem. From adaptive cruise control to blind-spot detection and lane-departure warning, carmakers are exploring a myriad of image sensors, along with technologies like radars and optics, to make driving as safe and intelligent as possible. While charge-coupled device (CCD)-based image sensors have pervaded the automotive scene for sometime, advances in CMOS imaging has opened the door to single-chip silicon cameras.

Besides low power consumption and integration, as both the image sensor and the processing circuitry are based on the same fine geometry standard logic process, the CMOS imaging technology has improved in performance to match that of CCDs at lower cost and smaller form factor. Furthermore, extended operating temperature ranges allow these devices to withstand extreme temperatures from -40 °C to +105 °C, providing dependable operation under severe automotive conditions. Consequently, several automotive applications have emerged for CMOS image sensors. Some of these include rear view assist, lane tracking or lane-departure warning, 360 ° view around the car (no blind spots), obstacle detection avoidance systems, blind spot detection, parking assistance and adaptive cruise control.

“The gap has been closing from both directions on performance (CCD) benefits vs. cost (CMOS), so the automotive market will remain split between the two technologies for now — depending upon application requirements for image quality vs. compactness and cost,” stated Mark Fitzgerald, senior automotive analyst at market research firm Strategy Analytics. Future systems are expected to favor CMOS imaging solutions, he added. Few automotive applications require image quality of the order that is required by other industry areas (e.g., multimega pixel digital cameras), and Strategy Analytics' research indicates that CMOS devices will be capable of supplying the required image quality, even at automotive-spec temperatures, for most applications.

Hence, several suppliers have emerged with new reliable high-quality CMOS image sensors that are designed to promote safer and smarter driving. Key players are AMI Semiconductor, Avago Technologies (formerly Agilent Technologies) Cypress Semiconductor, Iteris Inc., Micron, Melexis Semiconductors, OmniVision and STMicroelectronics, amongst others. Iteris Inc., a proponent of vision-based technology for driver safety, in fact, was one of the early adopters of CMOS imaging. Its lane-departure warning (LDW) system based on CMOS image sensors was first deployed in commercial trucks in the United States and Europe. Further improvements in performance and cost has enabled the developer to migrate to passenger cars with the first LDW system installed by Infinity in the fall of 2004 as an option on its FX cross SUVs. Lately, it has become available as an option in all the 2006 Infinity mid-size luxury sedans. According to Iteris, its LDW system was the first of its kind to be deployed in the commercial truck and passenger car markets and is in mass production in Europe and the United States.

Avago Technologies, who is also eyeing a number of safety-related automotive applications for its significantly improved CMOS image sensors, has projected some market numbers for CMOS cameras in vehicles of all types. Combining its internal research with market data from established research firms, Avago's study estimates that by 2008 some 40 million CMOS camera units will be consumed by automobiles around the world. The study shows that in 2005 the estimated worldwide consumption of CMOS cameras was around 10 million units. Avago believes that its refurbished low-light single-chip megapixel CMOS camera rivals the performance of CCDs and is ready to take them on in a variety of applications including automotive.

Thus, the proponents of CMOS imaging are confident that CMOS is at a point where it can address the needs of carmakers in terms of cost, form, performance and reliability. And they are foreseeing rapid growth for this technology in this marketplace.

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